Heretofore, in general, a height-adjusting device having a lock spring and a shaft disposed within a coil portion of the lock spring and holding an armrest at an arbitrary position by frictional resistance generated between the coil portion and the shaft has been publicly known (for example, Japanese Utility Model Application Laid-Open No. 5-53547).
The prior art device has been carrying a problem of requiring an operating lever to increase and decrease the frictional resistance between the coil portion and the shaft.
Further, the prior art device has caused trouble in the position adjustment method of the armrest.